What are flatworms?

Flatworms, members of Phylum Platyhelminthes, which means a "flat worm" in Greek, are relatively simple animals without real coeloma or body cavity. Unlike Cnidarians, such as jellyfish, who have only two germs and whose ancestors have never had coeloma, flat worms are tripleblastic (they have three germ layers) and develop from more complex animals with coelomas. Initially, it was assumed that flat worms were among the protosomes of the basal (large categories of animals), but it was found that this only applies to groups ACOELA and Nemertermatida. These animals then got their own phylum, Acoelomorph. In Ireland and Scotland, one flat worm, ArthurDendyus triangulatus , was so successful that since its accidental introduction at the age of 60, he had largely replaced the indigenous earthworms. This is an interesting example of acoelomate species is overcome by the types of coelomate on the ground, which is a relatively rare occurrence. Usually, akoelomates are more successful in water where they are better padded from the physical impact. BecauseFlat worms are an acoelomate, their bodies do not "give", which means that external pressure can easily cause organ damage.

Flatworms are wild or parasitic and move from microscopic to more than 90 ft (27 m) long, in the case of tapeworm, which is located in the intestinal tract of vertebrates. There are four classes of flat worms: trematode (Flukes), Pestoda (tapeworm), monogenea (small fish parasites) and turbullaria (carnivorous wilder worms). Flukes are the parasites of vertebrates and molluscs, while tapeworms are vertebrate parasites. Basically, three of the four classes of flat worms are parasites, while one lives freely. Free -living flat worms are characterized by slightly more complex morphology, such as steel (eye stains) that detect ambient light and ear (ear flaps) that sensing water streams.

There are about 25,000 types of flat worms, which makes them the largestACOELOMAT FYLA. The vast majority of animals of species (> 99%) are coelomate, although some animals of acoelomates such as nematodes are extremely large, they are found in every habitable environment. Like other Akoelomates and some coelomates, flat worms move through undulating movement. The parasitic flat worms connect to its host using a haptor, a specialized structure that adheres to the host and allows feeding.